This invention relates to contacting arrangements, including packing grates or panels, for mass transfer and heat exchange operations.
The term "mass transfer" as used herein includes chemical processes by which apparatus such as a scrubber unit absorbs contaminated gas molecules, sub-micron mist and particulates into a scrubbing liquid. Scrubber units used for mass transfer can have a wide variety of configurations and various orientations. To explain the process simply, mass transfer can involve a contaminated air stream moving through a mixing chamber. A liquid sprayed into the chamber is caused to mix with the air stream so that contaminated gas molecules are dissolved by contacting with the liquid and are removed from the air stream. This process relies on the natural affinity, or attraction, of the contaminant molecules to the scrubbing liquid solvent which may be plant water or a liquid that includes chemical solvents to improve the absorption of certain chemical contaminants. The efficiency of such a mass transfer process can be enhanced by introducing a packing media into the mixing chamber to create turbulence within the air stream, forcing the molecules of the scrubbing liquid and the contaminants into intimate contact.
It is known to provide crossflow packed bed scrubbers for environmental control applications which require contaminant gas absorption with or without particle removal. These known scrubbers involve a scrubbing liquid flowing vertically through the scrubber mixing chamber perpendicular to the contaminated airstream which can be drawn or forced through the chamber by means of a fan. Typically, the mixing chamber contains so called random packing material which can be made of a suitable plastic and which maximizes contact between the liquid and gas streams. After the scrubbing liquid passes through the packing material, it falls into a suitable sump located below the mixing chamber. Such known packed bed scrubbers are, for example, sold by Plasticair Inc. of Mississauga, Ontario, Canada, including Plasticair's HCS/HS series of scrubbers.
In addition to random packing material, it is also known to employ a plurality of stacked contacting grates for a mass transfer operation. For example, U.S Pat. No. 4,107,241 issued Aug. 15, 1978 to Raschig G.m.b.H. teaches a contacting grate made from a set of laterally spaced, parallel first strips and a set of laterally spaced second strips which extend transversely to the first strips. Each of the second strips is sloped at an oblique angle to the longitudinal direction of the first strips of the grate and this oblique angle is the same for all of the second strips of the grate. The second strips of the grates define zig-zag flow passages. The second strips repeatedly deflect vapours rising between these strips and are wetted by a liquid flowing counter-current to the vapours and in contact therewith.
U.S. Pat. No. 4,532,086 which issued Jul. 30, 1985 to Sulzer Brothers Ltd. describes packing that is made of one-piece layers and that can be used in mass transfer, direct heat exchange and mixing. The packing layers are constructed with parallel edge strips between which extend a number of parallel, angularly disposed deflecting members. The packing layers are made from flat sheet metal bodies which can be punched and bent to form the layers. In the alternative, the layers can be injection molded and made of plastics.
Recent U.S. Pat. No. 5,490,958 which issued Feb. 13, 1996 to In C. Lim describes a filler designed for a cooling tower, the filler being in the form of a rectangular frame having two vertically extending rods located along the vertical edges of the frame and a number of horizontally extending rods. A series of similar protrusions, each of which comprises two connected triangular plate sections, extend between adjacent horizontal rods. The protrusions extend horizontally a certain distance from the vertical plane formed by the rods. Male-female type connectors are provided at the corners to permit adjacent filler plates or grates to be connected to one another.
It is an object of the present invention to provide a contacting apparatus that in use is able to provide efficient mass transfer or heat exchange and that has a wide variety of possible applications.
It is a further object of the present invention to provide an improved contacting apparatus suitable for mass transfer or heat exchange which can be manufactured at a very reasonable cost using known manufacturing techniques.
It is an additional object of the present invention to provide a contacting apparatus having a wide variety of applications, particularly for mass transfer or heat exchange, which apparatus includes a supporting framework and a number of small protruding members mounted on supporting bars of the framework.